Electrochemical measuring devices have been commonly used to determine the concentration of analytes in body fluids. For example, in blood-glucose testing, a blood sample may be dropped at a measuring end of a test strip that is applied with an enzyme, and then the test strip may be inserted into a glucose meter to determine the concentration of glucose in the blood sample.
In the conventional art, the test strip is provided with a working electrode and a reference electrode to form a reaction region. The reaction region is applied with the enzyme so that when a test sample reacts with the enzyme, a chemical response is generated. When in use, the test strip is inserted in the glucose meter so that the glucose meter can read the chemical response in order to calculate the concentration of glucose in the blood sample.
However, as a result of variances in manufacturing of the test strips, calibration is needed before a particular batch of the test strips may be used with the glucose meter to obtain accurate test results. In the conventional art, the test strips are associated respective code patterns. The code patterns are normally formed by providing varying connectivities between any two contact pads provided on the test strips. The connectivities between any two contact pads will produce logic 1 or logic 0 as outputs for the glucose meter to read and to calibrate the glucose meter accordingly. As a result, the conventional glucose meter can compensate for the manufacturing variations on different batches of test strips automatically, before a user start to use the meter.
One common problem in the conventional art is the amount of coding information that can be encoded in the test strips for calibration purpose. As an example, a chip with eight pins provided within the conventional glucose meter can correspond to a test strip with eight contact pads. A common arrangement of the eight contact pads may be 2 rows of 4 contact pads at one end of any given test strip. Then, depending on the status of the electrical connectivities between one of the contact pads and a pre-defined pin, such as a ground pin, a logical value of 1 or 0 is outputted, thereby yielding a maximum of 16 codes to be used for auto-calibration purpose. Such limitation hinders the optimal use of the glucose meter and test strips.
Therefore, what is needed is a method of improving the number of auto-calibration codes that may be carried in the test strip without changing the existing structure and configuration of the glucose meter and the test strip and device for same.